1. family and parenting
2. motherhood
3. pregnancy

4
Pregnancy and Prenatal
Development
Karen Lutke and
Fetal Alcohol Syndrome
Focus
If I could have watched you grow
as a magical mother might,
if I could have seen through my magical transparent belly,
there would have been such ripening within. . . .
Prenatal Development:
Three Stages
—Anne Sexton, Live or Let Die, 1966
Focus
Karen Lutke and Fetal Alcohol Syndrome
Fetal alcohol syndrome (FAS) and fetal alcohol effects (FAS/E) are clusters of abnormalities
shown by children whose mothers drank during pregnancy, and are leading causes of mental
retardation. But in the late 1970s, when Jan Lutke adopted the first of her eight adopted children diagnosed with FAS/E, the facts about FAS were not widely publicized or scientifically
investigated, though the syndrome had been observed for centuries.
The child, a girl named Karen, was diagnosed at age 3 with FAS. She was removed from
her birth mother soon after she was born and was placed in a succession of family and fostercare homes for the first 3 years of her life. Her disruptive behaviour and hyperactivity made it
difficult for caregivers to cope, and she was ultimately placed in a resource facility before being adopted by Lutke.
Seventeen years later, as Lutke relates in Works in Progress: The Meaning of Success for
Individuals with FAS/E (Lutke, 2000), Karen is typical of young Canadian adults with FAS.
She is a self-assured young woman, who works as a dog-groomer, and she gives public talks
on FAS. Despite her successes, she has had to overcome the challenges of a lower-thanaverage IQ, immature social and emotional functioning, and susceptibility to perseveration, repeating stereotyped behaviour. Throughout her life, in particular during her adolescence, a key
factor in her successful development was unobtrusive supervision by peer mentors, older unaffected siblings, adult friends, and social services staff. This supervision worked to protect her
from poor decisions that could have led to dangerous situations. With an emphasis on her
strengths, Karen has acquired skills needed for active and independent living, while at the
same time developing techniques for overcoming the challenges of potentially difficult behaviour, particularly that associated with perseveration.
Fetal alcohol syndrome had been identified during the 1970s, while Karen was growing
up. Once alcohol enters a fetus’s bloodstream, it remains there in high concentrations for long
periods of time, causing brain damage and harming other body organs. There is no cure. As
one medical expert wrote, “for the fetus the hangover may last a lifetime” (Enloe, 1980, p. 15).
Germinal Stage (Fertilization to
2 Weeks)
Embryonic Stage (2 to 8 Weeks)
Fetal Stage (8 Weeks to Birth)
Prenatal Development:
Environmental Influences
Maternal Factors
Paternal Factors
Monitoring Prenatal
Development
● ● ●
or students of child development, the story of Karen Lutke is a hopeful note on the successes that are possible with a supportive home environment, but also a reminder of the
responsibility prospective biological parents have for the crucial development that occurs
before birth. The uterus is the developing child’s first environment, and its impact on the child
is immense. In addition to what the mother does and what happens to her, there are other environmental influences, from those that affect the father’s sperm to the technological, social,
and cultural environment, which may affect the kind of prenatal care a woman gets.
F
73
In this chapter we begin by looking at the experience of pregnancy and how prospective
parents prepare for a birth. We trace how the fertilized ovum becomes an embryo and then a fetus, already with a personality of its own. Then we discuss environmental factors that can affect
the developing person-to-be, describe techniques for determining whether development is proceeding normally, and explain the importance of prenatal care.
After you have read and studied this chapter, you should be able to answer each of the
Guidepost questions that appear at the top of the next page. Look for them again in the margins,
where they point to important concepts throughout the chapter. To check your understanding of
these Guideposts, review the end-of-chapter summary. Checkpoints located at periodic spots
throughout the chapter will help you verify your understanding of what you have read.
74
1. What are the three stages of prenatal development, and what happens during each
stage?
2. What can fetuses do?
3. What environmental influences can affect prenatal development?
Guideposts
for Study
4. What techniques can assess a fetus’s health and well-being, and what is the
importance of prenatal care?
Prenatal Development: Three Stages
Guidepost 1
If you had been born in China, you would probably celebrate your birthday on your estimated date of conception rather than your date of birth. This Chinese custom recognizes the
importance of gestation, the approximately 9-month (or 266-day) period of development
between conception and birth. Scientists, too, date gestational age from conception.
What turns a fertilized ovum, or zygote, into a creature with a specific shape and pattern? Research suggests that an identifiable group of genes is responsible for this transformation in vertebrates, presumably including human beings. These genes produce molecules
called morphogens, which are switched on after fertilization and begin sculpting arms,
hands, fingers, vertebrae, ribs, a brain, and other body parts (Echeland et al., 1993; Kraus,
Concordet, & Ingham, 1993; Riddle, Johnson, Laufer, & Tabin, 1993). Scientists are also
learning about the environment inside the womb and how it affects the developing person.
Prenatal development takes place in three stages: germinal, embryonic, and fetal.
(Table 4-1 gives a month-by-month description.) During these three stages of gestation, the
original single-celled zygote grows into an embryo and then a fetus. Both before and after
birth, development proceeds according to two fundamental principles. Growth and motor
development occur from top down and from the centre of the body outward.
The cephalocaudal principle (from Latin, meaning “head to tail”) dictates that development proceeds from the head to the lower part of the trunk. An embryo’s head, brain, and
eyes develop earliest and are disproportionately large until the other parts catch up. At 2
months of gestation, the embryo’s head is half the length of the body. By the time of birth,
the head is only one-fourth the length of the body but is still disproportionately large. According to the proximodistal principle (from Latin, “near to far”), development proceeds
from parts near the centre of the body to outer ones. The embryo’s head and trunk develop
before the limbs, and the arms and legs before the fingers and toes.
Germinal Stage (Fertilization to 2 Weeks)
During the germinal stage, from fertilization to about 2 weeks of gestational age, the
zygote divides, becomes more complex, and is implanted in the wall of the uterus (see
Figure 4-1).
Within 36 hours after fertilization, the zygote enters a period of rapid cell division and
duplication, or mitosis (refer back to chapter 3). Seventy-two hours after fertilization, it has
divided into 16 to 32 cells; a day later it has 64 cells. This division continues until the original single cell has developed into the 800 billion or more specialized cells that make up the
human body.
While the fertilized ovum is dividing, it is also making its way down the Fallopian tube
to the uterus, a journey of 3 or 4 days. Its form changes into a fluid-filled sphere, a blastocyst, which floats freely in the uterus for a day or two and then begins to implant itself in
the uterine wall. As cell differentiation begins, some cells around the edge of the blastocyst
cluster on one side to form the embryonic disk, a thickened cell mass from which the embryo begins to develop. This mass is already differentiating into two layers. The upper
layer, the ectoderm, will become the outer layer of skin, the nails, hair, teeth, sensory organs, and the nervous system, including the brain and spinal cord. The lower layer, the endoderm, will become the digestive system, liver, pancreas, salivary glands, and respiratory
Chapter 4
What are the three stages of
prenatal development, and what
happens during each stage?
cephalocaudal principle
Principle that development
proceeds in a head-to-tail
direction; that is, upper parts of
the body develop before lower
parts
proximodistal principle Principle
that development proceeds from
within to without; that is, parts of
the body near the centre develop
before the extremities
germinal stage First 2 weeks of
prenatal development,
characterized by rapid cell
division, increasing complexity
and differentiation, and
implantation in the wall of the
uterus
Pregnancy and Prenatal Development
75
Table 4-1
Prenatal Development
Month
Description
During the first month, growth is more rapid than at any other time during prenatal or postnatal
life: The embryo reaches a size 10,000 times greater than the zygote. By the end of the first
month, it measures about 1.5 cm in length. Blood flows through its veins and arteries, which
are very small. It has a minuscule heart, beating 65 times a minute. It already has the
beginnings of a brain, kidneys, liver, and digestive tract. The umbilical cord, its lifeline to the
mother, is working. By looking very closely through a microscope, it is possible to see the
swellings on the head that will eventually become eyes, ears, mouth, and nose. Its sex cannot
yet be determined.
1 month
By the end of the second month, the organism is less than 2.5 cm long and weighs only
2.2 g. Its head is half its total body length. Facial parts are clearly developed, with tongue and
teeth buds. The arms have hands, fingers, and thumbs, and the legs have knees, ankles, and
toes. It has a thin covering of skin and can make handprints and footprints. Bone cells appear
at about 8 weeks. Brain impulses coordinate the function of the organ system. Sex organs are
developing; the heartbeat is steady. The stomach produces digestive juices; the liver, blood
cells. The kidneys remove uric acid from the blood. The skin is now sensitive enough to react
to tactile stimulation. If an aborted 8-week-old fetus is stroked, it reacts by flexing its trunk,
extending its head, and moving back its arms.
2 months
By the end of the third month, the fetus weighs about 30 g, and measures about 7.5 cm in
length. It has fingernails, toenails, eyelids (still closed), vocal cords, lips, and a prominent nose.
Its head is still large—about one-third its total length—and its forehead is high. Sex can easily
be determined. The organ systems are functioning, and so the fetus may now breathe,
swallow amniotic fluid into the lungs and expel it, and occasionally urinate. Its ribs and
vertebrae have turned into cartilage. The fetus can now make a variety of specialized
responses: It can move its legs, feet, thumbs, and head; its mouth can open and close and
swallow. If its eyelids are touched, it squints; if its palm is touched, it makes a partial fist; if its
lip is touched, it will suck; and if the sole of the foot is stroked, the toes will fan out. These
reflexes will be present at birth but most will be less easily elicited during the first months of life
because brain development will permit voluntary control.
3 months
The body is catching up to the head, which is now only one-fourth the total body length, the
same proportion it will be at birth. The fetus now measures 20 to 25 cm and weighs about
175 g. The umbilical cord is as long as the fetus and will continue to grow with it. The placenta
is now fully developed. The mother may be able to feel the fetus kicking, a movement known
as quickening, which some societies and religious groups consider the beginning of human
life. The reflex activities that appeared in the third month are now brisker because of increased
muscular development.
4 months
The fetus, now weighing about 350 to 450 g and measuring about 30 cm, begins to show
signs of an individual personality. It has definite sleep–wake patterns, has a favourite position
in the uterus (called its lie), and becomes more active—kicking, stretching, squirming, and
even hiccupping. By putting an ear to the mother’s abdomen, it is possible to hear the fetal
heartbeat. The sweat and sebaceous glands are functioning. The respiratory system is not yet
adequate to sustain life outside the womb; a baby born at this time does not usually survive.
Coarse hair has begun to grow for eyebrows and eyelashes, fine hair is on the head, and a
woolly hair called lanugo covers the body.
5 months
76
Part 2
Beginnings
Table 4-1
Prenatal Development (Continued)
Month
Description
The rate of fetal growth has slowed down a little—by the end of the sixth month, the fetus is
about 35 cm long and weighs 575 g. It has fat pads under the skin; the eyes are complete,
opening, closing, and looking in all directions. It can hear, and it can make a fist with a strong
grip. A fetus born during the sixth month still has only a slight chance of survival, because the
breathing apparatus has not matured. However, some fetuses of this age do survive outside
the womb.
6 months
By the end of the seventh month, the fetus, about 40 cm long and weighing 1.5 to 2.5 kg,
now has fully developed reflex patterns. It cries, breathes, swallows, and may suck its thumb.
The lanugo may disappear at about this time, or it may remain until shortly after birth. Head
hair may continue to grow. The chances that a fetus weighing at least 1.5 kg will survive are
fairly good, provided it receives intensive medical attention. It will probably need to be kept in
an incubator until a weight of 2.5 kg is attained.
7 months
The 8-month-old fetus is 45 to 50 cm long and weighs between 2 and 3 kg. Its living quarters
are becoming cramped, and so its movements are curtailed. During this month and the next,
a layer of fat is developing over the fetus’s entire body, which will enable it to adjust to varying
temperatures outside the womb.
8 months
About a week before birth, the fetus stops growing, having reached an average weight of
about 3.5 kg and a length of about 50 cm, with boys tending to be a little longer and heavier
than girls. Fat pads continue to form, the organ systems are operating more efficiently, the
heart rate increases, and more wastes are expelled through the umbilical cord. The reddish
colour of the skin is fading. At birth, the fetus will have been in the womb for about 266 days,
although gestational age is usually estimated at 280 days, since most doctors date the
pregnancy from the mother’s last menstrual period.
9 months–newborn
Note: Even in these early stages, individuals differ. The figures and descriptions given here represent averages.
Chapter 4
Pregnancy and Prenatal Development
77
system. Later a middle layer, the mesoderm,
will develop and differentiate into the inner
Outer uterine wall
4 cells
layer of skin, muscles, skeleton, and excre(48 hours)
16–32 cells
tory and circulatory systems.
(3 days)
Other parts of the blastocyst begin to develop into organs that will nurture and protect the unborn child: the placenta, the
Continued cell division
umbilical cord, and the amniotic sac with its
and formation of
Ovary
outermost membrane, the chorion. The plainner cell mass
centa, which has several important functions,
(4–5 days)
will be connected to the embryo by the umFertilization
Embryo attaching
bilical cord. Through this cord the placenta
to uterine wall
delivers oxygen and nourishment to the de(6–7 days)
Fallopian tube
veloping baby and removes its body wastes.
Embryo (now
Beginning: Single-celled
The placenta also helps to combat internal inblastocyst)
mature ovum leaves
fection and gives the unborn child immunity
joined to
ovary
uterine wall
to various diseases. It produces the hormones
(11–12 days)
that support pregnancy, prepares the mother’s
breasts for lactation, and eventually stimuFigure 4-1
lates the uterine contractions that will expel
Early development of a human embryo. This simplified diagram shows the progress of the
the baby from the mother’s body. The amniovum as it leaves the ovary, is fertilized in the Fallopian tube, and then divides while
otic sac is a fluid-filled membrane that entravelling to the lining of the uterus. Now a blastocyst, it is implanted in the uterus, where it
cases the developing baby, protecting it and
will grow larger and more complex until it is ready to be born.
giving it room to move. The trophoblast, the
outer cell layer of the blastocyst (which becomes part of the placenta), produces tiny threadlike structures that penetrate the lining of
the uterine wall and enable the developing organism to cling there until it is fully implanted
in the uterine lining.
Only about 10 to 20 per cent of fertilized eggs complete the task of implantation and
continue to develop. Researchers have identified a gene called Hoxa10, which appears to
affect whether an embryo will be successfully implanted in the uterine wall (Taylor, Arici,
Olive, & Igarashi, 1998). Timing appears to be important; implantation more than 8 to 10
days after ovulation increases the risk of pregnancy loss (Wilcox, Baird, & Weinberg,
1999).
2 cells
Cell
(36 hours) division
Embryonic Stage (2 to 8 Weeks)
embryonic stage Second stage
of gestation (2 to 8 weeks),
characterized by rapid growth and
development of major body
systems and organs
spontaneous abortion Natural
expulsion from the uterus of an
embryo or fetus that cannot
survive outside the womb; also
called miscarriage
78
Part 2
Beginnings
During the embryonic stage, the second stage of gestation, from about 2 to 8 weeks, the
organs and major body systems—respiratory, digestive, and nervous—develop rapidly.
This is a critical period, when the embryo is most vulnerable to destructive influences in the
prenatal environment (see Figure 4-2). An organ system or structure that is still developing
at the time of exposure is most likely to be affected. Defects that occur later in pregnancy
are likely to be less serious.
The most severely defective embryos seldom survive beyond the first trimester, or 3month period, of pregnancy. A spontaneous abortion, commonly called a miscarriage, is
the expulsion from the uterus of an embryo or fetus that is unable to survive outside the
womb. Most miscarriages result from abnormal pregnancies; about 50 to 70 per cent involve chromosomal abnormalities.
Males are more likely than females to be spontaneously aborted or stillborn (dead at
birth). Thus, although about 125 males are conceived for every 100 females—a fact that has
been attributed to the greater mobility of sperm carrying the smaller Y chromosome—only
105 boys are born for every 100 girls. Males’ greater vulnerability continues after birth:
More of them die early in life (Statistics Canada, 1997), and at every age they are more susceptible to many disorders. Furthermore, the proportion of male births appears to be falling
in Canada, the United States, and several European countries, while the incidence of birth
defects among males is rising, perhaps reflecting effects of environmental pollutants
(Davis, Gottlieb, & Stampnitzky, 1998).
Figure 4-2
When birth defects occur. Body
parts and systems are most
vulnerable to damage when they are
developing most rapidly (dark
areas), generally within the first
trimester of pregnancy.
Weeks after conception:
1
2
3
4
5
6
7
8
9
16
20–38
Central nervous system
Heart
Arms
Note: Intervals of time are not all equal.
Eyes
Source: J. E. Brody, 1995; data from
March of Dimes
Legs
Teeth
Palate
External genitalia
Ears
Fetal Stage (8 Weeks to Birth)
The appearance of the first bone cells at about 8 weeks signals the fetal stage, the final
stage of gestation. During this period, the fetus grows rapidly to about 20 times its previous
length, and organs and body systems become more complex. Right up to birth, “finishing
touches” such as fingernails, toenails, and eyelids develop.
Fetuses are not passive passengers in their mothers’ wombs. They breathe, kick, turn,
flex their bodies, do somersaults, squint, swallow, make fists, hiccup, and suck their
thumbs. The flexible membranes of the uterine walls and amniotic sac, which surround the
protective buffer of amniotic fluid, permit and stimulate limited movement.
Scientists can observe fetal movement through ultrasound, using high-frequency
sound waves to detect the outline of the fetus. Other instruments can monitor heart rate,
changes in activity level, states of sleep and wakefulness, and cardiac reactivity. In one
study, fetuses monitored from 20 weeks of gestation until term had decreasing but more
variable heart rates—possibly in response to the increasing stress of the mother’s pregnancy—and greater cardiac response to stimulation. They also showed less, but more vigorous, activity—perhaps a result of the increasing difficulty of movement for a growing
fetus in a constricted environment, as well as of maturation of the nervous system. A significant “jump” in all these aspects of fetal development seems to occur between 28 and 32
weeks; it may help explain why infants born prematurely at this time are more likely to survive and flourish than those born earlier (DiPietro et al., 1996).
The movements and activity level of fetuses show marked individual differences, and
their heart rates vary in regularity and speed. There also are differences between males and
females. Male fetuses, regardless of size, are more active and tend to move more vigorously
than female fetuses throughout gestation. Thus infant boys’ tendency to be more active than
girls may be at least partly inborn (DiPietro et al., 1996).
Apparent differences in temperament appear as early as 24 weeks of gestation and remain stable throughout the prenatal period and beyond. Three to 6 months after birth, infants who had moved around more in the womb tended to be more difficult, unpredictable,
and active and less adaptable, according to their mothers, than infants whose fetal activity
had been calmer (DiPietro, Hodgson, Costigan, & Johnson, 1996). It is possible, however,
that the mothers’ reports about their infants’ temperament were influenced by perceptions
formed during pregnancy.
Beginning at about week 12 of gestation, the fetus swallows and inhales some of the amniotic fluid in which it floats. The amniotic fluid contains substances that cross the placenta
from the mother’s bloodstream and enter the fetus’s own bloodstream. Taking in these substances may stimulate the budding senses of taste and smell and may contribute to the
Chapter 4
Guidepost 2
What can fetuses do?
fetal stage Final stage of
gestation (from 8 weeks to birth),
characterized by increased detail
of body parts and greatly enlarged
body size
ultrasound Prenatal medical
procedure using high-frequency
sound waves to detect the outline
of a fetus and its movements, in
order to determine whether a
pregnancy is progressing normally
Pregnancy and Prenatal Development
79
Can you . . .
✔ Identify two principles that
govern physical development
and give examples of their
application during the prenatal
period?
✔ Describe how a zygote
becomes an embryo?
✔ Explain why defects and
miscarriages are most likely to
occur during the embryonic
stage?
✔ Describe findings about fetal
activity, sensory development,
and memory?
Guidepost 3
What environmental influences
can affect prenatal development?
development of organs needed for breathing and digestion (Mennella & Beauchamp, 1996a;
Ronca & Alberts, 1995; Smotherman & Robinson, 1995, 1996). Mature taste cells appear at
about 14 weeks of gestation. The olfactory system, which controls the sense of smell, is also
well developed before birth (Bartoshuk & Beauchamp, 1994; Mennella & Beauchamp,
1996a).
Fetuses also respond to the mother’s voice and heartbeat and the vibrations of her
body, suggesting that they can hear and feel. Familiarity with the mother’s voice may have
a basic survival function: to help newborns locate the source of food. Hungry infants, no
matter on which side they are held, turn toward the breast in the direction from which they
hear the mother’s voice (Noirot & Algeria, 1983, cited in Rovee-Collier, 1996). Responses
to sound and vibration seem to begin at 26 weeks of gestation, rise, and then reach a plateau
at about 32 weeks (Kisilevsky, Muir, & Low, 1992).
Fetuses seem to learn and remember. In one experiment, 3-day-old infants sucked
more on a nipple that activated a recording of a story their mother had frequently read aloud
during the last 6 weeks of pregnancy than they did on nipples that activated recordings of
two other stories. Apparently, the infants recognized the pattern of sound they had heard in
the womb. A control group, whose mothers had not recited a story before birth, responded
equally to all three recordings (DeCasper & Spence, 1986). Similar experiments have
found that newborns 2 to 4 days old prefer musical and speech sequences heard before
birth. They also prefer their mother’s voice to those of other women, female voices to male
voices, and their mother’s native language to another language (DeCasper & Fifer, 1980;
DeCasper & Spence, 1986; Moon, Cooper, & Fifer, 1993; Fifer & Moon, 1995; Lecanuet,
Granier-Deferre, & Busnel, 1995).
How do we know that these preferences develop before rather than after birth? Newborns were given the choice of sucking to turn on a recording of the mother’s voice or a
“filtered” version of her voice as it might sound in the womb. The newborns sucked more
often to turn on the filtered version, suggesting that fetuses develop a preference for the
kinds of sounds they hear before birth ( Fifer & Moon, 1995; Moon & Fifer, 1990).
Prenatal Development: Environmental
Influences
The pervasive influence of the prenatal environment underlines the importance of providing an unborn child with the best possible start in life. Only recently have scientists become
aware of some of the myriad environmental influences that can negatively affect the
developing organism. The role of the father used to be virtually ignored; today we know
that various environmental factors can affect a man’s sperm and the children he fathers. Although the mother’s role has been recognized far longer, researchers are still discovering
environmental hazards that can affect her fetus. Some of these findings have led to ethical
debate over a woman’s responsibility for avoiding activities that may harm her unborn child
(see Box 4-1).
Maternal Factors
teratogenic Capable of causing
birth defects
80
Part 2
Beginnings
Since the prenatal environment is the mother’s body, virtually everything that impinges on
her well-being, from her diet to her moods, may alter her unborn child’s environment and
affect its growth.
Not all environmental hazards are equally risky for all fetuses. Some factors that are
teratogenic (birth defect–producing) in some cases have little or no effect in others. The
timing of exposure to a teratogen, its intensity, and its interaction with other factors may be
important (refer back to Figure 4-2).
Vulnerability may depend on a gene in either the fetus or the mother. For example,
fetuses with a particular variant of a growth gene, called transforming growth factor alpha,
have six times more risk than other fetuses of developing a cleft palate if the mother
The Social World
Box 4-1
Fetal Welfare versus Mothers’ Rights
A Winnipeg woman is apprehended by Child and Family Services for inhaling solvents while pregnant. A court orders her to
enter a treatment program after finding her mentally incompetent, despite contrary evidence in a psychiatric report. A year
later, the decision is overturned by the Manitoba Court of Appeal, and by the Supreme Court of Canada, arguing that there is
no legal basis to order addicted pregnant women to seek treatment to protect the developing fetus (Kuxhaus, 1997).
In this case, the issue is the conflict between protection of a
fetus and a woman’s right to privacy or to make her own decisions about her body. It is tempting to require a pregnant woman
to adopt practices that will ensure her baby’s health, or to stop or
punish her if she doesn’t. But what about her personal freedom?
Can civil rights be abrogated for the protection of the unborn?
The argument about the right to choose abortion, which rests
on similar grounds, is far from settled. But the example just
given deals with a different aspect of the problem. What can or
should society do about a woman who does not choose abortion,
but instead goes on carrying her baby while engaging in behaviour destructive to it, or refuses tests or treatment that medical
providers consider essential to its welfare?
Should a woman be forced to submit to intrusive procedures
that pose a risk to her, such as a surgical delivery or intrauterine
transfusions, when doctors say such procedures are essential to
the delivery of a healthy baby? Should a woman from a fundamentalist sect that rejects modern medical care be taken into custody until she gives birth? Such measures have been invoked and
have been defended as protecting the rights of the unborn. But
women’s rights advocates claim that they reflect a view of
women as mere vehicles for carrying offspring, and not as persons in their own right (Greenhouse, 2000b).
Medical professionals warn that such measures also may
have important practical drawbacks. Legal coercion could jeopardize the doctor–patient relationship. Coercion could also open
the door to go further into pregnant women’s lives—demanding
prenatal screening and fetal surgery or restricting their diet,
work, and athletic and sexual activity (Kolder, Gallagher, & Parsons, 1987). For these reasons, the overwhelming attitude of
medical, legal, and social critics is that the state should intervene
only in circumstances in which there is a high risk of serious disease or a high degree of accuracy in the test for a defect, strong
evidence that the proposed treatment will be effective, danger
that deferring treatment until after birth will cause serious damage, minimal risk to the mother and modest interference with her
privacy, and persistent but unsuccessful efforts to educate her
and obtain her informed consent.
Does a woman have the right to knowingly ingest a substance, such as alcohol or another drug, that can permanently
damage her unborn child? Some advocates for fetal rights think
it should be against the law for pregnant women to smoke or use
alcohol, even though these activities are legal for other adults.
Other experts argue that incarceration for substance abuse is unworkable and self-defeating. They say that expectant mothers
who have a drinking or drug problem need education and treatment, not prosecution (Marwick, 1997, 1998). If failure to follow medical advice can bring forced surgery, confinement, or
criminal charges, some women may avoid doctors altogether and
thus deprive their fetuses of needed prenatal care (Nelson &
Marshall, 1998).
There has been no successful prosecution of a Canadian
woman for abusing dangerous substances while pregnant. An alternative, and likely more effective, way to help ensure that
pregnant women avoid ingesting harmful substances is public
education. As an example, across Canada provincial liquor
boards and commissions now employ advertising campaigns to
alert pregnant women to the dangers of alcohol consumption
during pregnancy.
?
What’s your view
Does society’s interest in protecting an unborn child justify coercive measures against pregnant women who ingest harmful
substances or refuse medically indicated treatment? Should
pregnant women who refuse to stop drinking or get treatment be
incarcerated until they give birth? Should mothers who repeatedly give birth to children with FAS be sterilized? Should liquor
companies be held liable if adequate warnings are not on their
products? Would your answers be the same regarding smoking
or use of cocaine or other potentially harmful substances?
!
Check it out
For more information on this topic, go to www.mcgrawhill.ca/
college/papalia.
smokes while pregnant, and almost nine times more risk if she smokes more than 10 cigarettes a day (Hwang et al., 1995). Women without the abnormal allele who smoke at least
20 cigarettes a day are at heightened risk of having babies with cleft palates, but their risk
is even greater if the abnormal gene is present (Shaw, Wasserman, et al., 1996).
Nutrition
Women need to eat more than usual when pregnant: typically, 300 to 500 more calories a
day, including extra protein. Pregnant women who gain between 10 and 20 kg are less
likely to miscarry or to bear babies who are stillborn or whose weight at birth is dangerously low (Abrams & Parker, 1990; Ventura, Martin, Curtin, & Mathews, 1999).
Chapter 4
Pregnancy and Prenatal Development
81
Malnutrition during fetal growth may have long-range effects. In rural Gambia,
in western Africa, people born during the “hungry” season, when foods from the previous
harvest are badly depleted, are 10 times more likely to die in early adulthood than people
born during other parts of the year (Moore et al., 1997). Psychiatric examinations of Dutch
military recruits whose mothers had been exposed to wartime famine during pregnancy
suggest that severe prenatal nutritional deficiencies in the first or second trimesters affect
the developing brain, increasing the risk of antisocial personality disorders at age 18
(Neugebauer, Hoek, & Susser, 1999).
Malnourished women who take dietary supplements while pregnant tend to have bigger, healthier, more active, and more visually alert infants (J. L. Brown, 1987; Vuori et al.,
1979); and women with low zinc levels who take daily zinc supplements are less likely to
have babies with low birth weight and small head circumference (Goldenberg et al., 1995).
However, certain vitamins (including A, B6, C, D, and K) can be harmful in excessive
amounts. Iodine deficiency, unless corrected before the third trimester of pregnancy, can
cause cretinism, which may involve severe neurological abnormalities or thyroid problems
(Cao et al., 1994; Hetzel, 1994).
Only recently have we learned of the critical importance of folic acid, or folate (a B vitamin) in a pregnant woman’s diet. For some time, scientists have known that China has the
highest incidence in the world of babies born with the neural-tube defects anencephaly and
spina bifida (refer back to Table 3-1), but it was not until the 1980s that researchers linked
that fact with the timing of the babies’ conception. Traditionally, Chinese couples marry in
January or February and try to conceive as soon as possible. That means pregnancies often
begin in the winter, when rural women have little access to fresh fruits and vegetables, important sources of folic acid.
After medical detective work established the lack of folic acid as a cause of neuraltube defects, China embarked on a massive program to give folic acid supplements to
prospective mothers, which resulted in a large reduction in the prevalence of these defects
(Berry et al., 1999). In Canada, women of childbearing age are now urged to include this
vitamin in their diets by eating plenty of fresh fruits and vegetables, or taking vitamin supplements, even before becoming pregnant, since damage from folic acid deficiency can occur during the early weeks of gestation (Society of Obstetricians and Gynaecologists of
Canada [SOGC], 1993). Increasing women’s folic acid consumption by just 0.4 mg each
day would reduce the incidence of neural-tube defects by at least half (AAP Committee on
Genetics, 1999; Centers for Disease Control and Prevention, 1999b; Daly, Kirke, Molloy,
Weir, & Scott, 1995). Canadian initiatives designed to promote healthy prenatal development, like the Healthy Babies, Healthy Children program in Ontario, and the Building Better Babies Pregnancy Outreach Program, operated by the Tillicum Haus Native Friendship
Centre in British Columbia, provide education and material support like food and vitamin
supplements to pregnant women.
Obese women also risk having children with neural-tube defects. Women who, before
pregnancy, weigh more than 80 kg or have an elevated body mass index (weight compared
with height) are more likely to produce babies with such defects, regardless of folate intake.
Obesity also increases the risk of other complications of pregnancy, including miscarriage, stillbirth, and neonatal death (death during the first month of life) (Cnattingius,
Bergstrom, Lipworth, & Kramer, 1998; Goldenberg & Tamura, 1996; G. M. Shaw, Velie,
& Schaffer, 1996; Werler, Louik, Shapiro, & Mitchell, 1996). Either overweight or
underweight can be risky: Among women having their first babies, those who were overweight before pregnancy had the most risk of stillbirth or of losing their babies during the
first week of life. On the other hand, underweight women are more likely to have dangerously small babies (Cnattingius et al., 1998).
Physical Activity
Moderate exercise does not seem to endanger the fetuses of healthy women (Carpenter et
al., 1988). Regular exercise prevents constipation and improves respiration, circulation,
muscle tone, and skin elasticity, all of which contribute to a more comfortable pregnancy
and an easier, safer delivery.
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Employment during pregnancy generally entails no special hazards. However, strenuous working conditions, occupational fatigue, and long working hours may be associated
with a greater risk of premature birth (Luke et al., 1995).
The Society of Obstetricians and Gynaecologists of Canada (2000) recommends that
women in low-risk pregnancies be guided by their own abilities and stamina. The safest
course seems to be for pregnant women to exercise moderately, not pushing themselves and
not raising their heart rate above 150, and, as with any exercise, tapering off at the end of
each session rather than stopping abruptly.
Can you . . .
✔ Summarize recommendations
concerning an expectant
mother’s diet and physical
activity?
Drug Intake
Practically everything an expectant mother takes in makes its way to the uterus. Drugs may
cross the placenta, just as oxygen, carbon dioxide, and water do. Vulnerability is greatest in
the first few months of gestation, when development is most rapid. Some problems resulting
from prenatal exposure to drugs can be treated if the presence of a drug can be detected early.
What are the effects of the use of specific drugs during pregnancy? Let’s look first at
medical drugs; then at alcohol, nicotine, and caffeine; and finally at some illegal drugs:
marijuana, opiates, and cocaine.
Medical Drugs It was once thought that the placenta protected the fetus against drugs the
mother took during pregnancy—until the early 1960s, when a tranquilizer called thalidomide was banned after it was found to have caused stunted or missing limbs, severe facial
deformities, and defective organs in some 12,000 babies worldwide, with about 120 survivors living in Canada today. The thalidomide disaster sensitized medical professionals
and the public to the potential dangers of taking drugs while pregnant. Today, nearly 30 drugs
have been found to be teratogenic in clinically recommended doses (Koren, Pastuszak, &
Ito, 1998). Among them are the antibiotic tetracycline; certain barbiturates, opiates, and
other central nervous system depressants; several hormones, including diethylstilbestrol
(DES) and androgens; certain anti-cancer drugs, such as methotrexate; Accutane, a drug
often prescribed for severe acne; and Aspirin and other nonsteroidal anti-inflammatory
drugs, which should be avoided during the third trimester.
Effects may be far-reaching and long-lasting. In one study, Danish men in their thirties
whose mothers had taken phenobarbital during pregnancy (especially during the last
trimester) had significantly lower verbal intelligence scores than a control group. Coming
from a lower socio-economic background or having been the product of an unwanted pregnancy tended to magnify the negative outcome, showing an interaction of environmental
factors before and after birth (Reinisch, Sanders, Mortensen, Psych, & Rubin, 1995).
The effects of taking a drug during pregnancy do not always show up immediately. In
the late 1940s and early 1950s, the synthetic hormone diethylstilbestrol (DES) was widely
prescribed (ineffectually, as it turned out) to prevent miscarriage. Not until years later,
when the daughters of women who had taken DES during pregnancy reached puberty, did
about 1 in 1,000 develop a rare form of vaginal or cervical cancer (Melnick, Cole,
Anderson, & Herbst, 1987). So far, “DES daughters” have shown no unusual risk of other
cancers (Hatch et al., 1998). However, they have had more trouble bearing their own children than other women do, with higher risks of miscarriage or premature delivery (A.
Barnes et al., 1980). In studies with mice, researchers have found that DES inhibits the activity of a gene called Writ-7a, which plays an important role in the development of the reproductive tract (Miller, Degenhart, & Sassoon, 1998).
Using prescription medication while breast-feeding is a cause for concern, given that
medications could pass into breast milk, affecting the nursing child. The Motherisk program at Toronto’s Hospital for Sick Children reports that most prescription drugs do not
pose a risk to the breast-fed infant; the major exceptions being medications for cancer therapy and anticonvulsants (Moretti, Lee, & Ito, 2000). Drugs of abuse, like alcohol, cocaine,
and amphetamines, should be avoided as they have been found to pass through to breast
milk. Pregnant women should not take over-the-counter drugs without consulting a doctor
(Koren et al., 1998); about one in four Canadian women reports using medication during
pregnancy (Human Resources Development Canada, 1996).
Chapter 4
Pregnancy and Prenatal Development
83
fetal alcohol syndrome (FAS)
Combination of mental, motor,
and developmental abnormalities
affecting the offspring of some
women who drink heavily during
pregnancy
• Thousands of adults now alive
suffered gross abnormalities
because, during the 1950s,
their mothers took the
tranquilizer thalidomide during
pregnancy. As a result, the use
of thalidomide was banned in
Canada and some other
countries. Now thalidomide
has been found to be effective
in treating or controlling many
illnesses, from mouth ulcers to
brain cancer. Should its use for
these purposes be permitted
even though there is a risk that
pregnant women might take
it? If so, what safeguards
should be required?
Alcohol Like Karen Lutke, about 1 infant in 750 suffers from fetal alcohol syndrome
(FAS), a combination of slow prenatal and postnatal growth, facial and bodily malformations, and disorders of the central nervous system. Problems related to the central nervous
system in infancy, can include poor sucking response, brain-wave abnormalities, and sleep
disturbances; and, throughout childhood, slow information processing, short attention span,
restlessness, irritability, hyperactivity, learning disabilities, retarded growth, and motor impairments. Prebirth exposure to alcohol seems to affect a portion of the corpus callosum,
which coordinates signals between the two hemispheres of the brain. In macaques (and,
presumably, in humans as well) the affected portion, toward the front of the head, is involved in initiating voluntary movement and other higher-order processing (Miller, Astley,
& Clarren, 1999).
For every child with FAS, as many as 10 others may be born with fetal alcohol effects.
This less severe condition can include mental retardation, retardation of intrauterine
growth, and minor congenital abnormalities.
Even moderate drinking may harm a fetus, and the more the mother drinks, the greater
the effect. According to research with rats, even a single drinking binge of 4 hours or more
can do tremendous damage to the developing brain (Ikonomidou et al., 2000). Moderate or
heavy drinking during pregnancy seems to alter the character of a newborn’s cry, an index
of neurobehavioural status. (So does moderate smoking during pregnancy.) Disturbed neurological and behavioural functioning may, in turn, affect early social interaction with the
mother, which is vital to emotional development (Nugent, Lester, Greene, WieczorekDeering, & O’Mahony, 1996).
Some FAS problems recede after birth; but others, such as retardation, behavioural and
learning problems, and hyperactivity, tend to persist. Unfortunately, enriching these children’s education or general environment does not seem to enhance their cognitive development (Kerns, Don, Mateer, & Streissguth, 1997; Spohr, Willms, & Steinhausen, 1993;
Streissguth et al., 1991; Strömland & Hellström, 1996). Because there is no known safe
level of drinking during pregnancy, it is best to avoid alcohol from the time a woman begins thinking about becoming pregnant until she stops breast-feeding (AAP Committee on
Substance Abuse and Committee on Children with Disabilities, 1993).
Nicotine About a quarter of Canadian women report smoking during pregnancy (Human
Resources Development Canada, 1996), with 84 per cent of smokers continuing throughout pregnancy, and 90 per cent doing so during the first trimester (CICH, 2000). Tobacco
use by pregnant women early in pregnancy can cause miscarriage, neonatal death, low birth
weight, and need for intensive care for infants (DiFranza & Lew, 1995).
Since women who smoke during pregnancy also tend to smoke after giving birth, it is
hard to separate the effects of prenatal and postnatal exposure. One study did this by examining 500 newborns about 48 hours after birth, while they were still in the hospital’s
non-smoking maternity ward and thus had not been exposed to smoking outside the womb.
Newborns whose mothers had smoked during pregnancy were shorter and lighter and had
poorer respiratory functioning than babies of non-smoking mothers (Stick, Burton, Gurrin,
Sly, & LeSouëf, 1996). A mother’s smoking during pregnancy may also increase her child’s
risk of cancer (Lackmann et al., 1999).
Smoking during pregnancy seems to have some of the same effects on children when
they reach school age as drinking during pregnancy: poor attention span, hyperactivity,
anxiety, learning and behaviour problems, perceptual-motor and linguistic problems, poor
IQ scores, low grade placement, and neurological problems (Landesman-Dwyer &
Emanuel, 1979; Milberger, Biederman, Faraone, Chen, & Jones, 1996; Naeye & Peters,
1984; D. Olds, Henderson, & Tatelbaum, 1994a, 1994b; Streissguth et al., 1984; Wakschlag
et al., 1997; Weitzman, Gortmaker, & Sobol, 1992; Wright et al., 1983). A 10-year longitudinal study of 6- to 23-year-old offspring of women who reported having smoked heavily during pregnancy found a fourfold increase in risk of conduct disorder in boys,
beginning before puberty, and a fivefold increased risk of drug dependence in girls, beginning in adolescence, in comparison with young people whose mothers had not smoked during pregnancy (Weissman, Warner, Wickramaratne, & Kandel, 1999). An 18-year Ottawa
study found both short-term and long-term effects: lowered birth weight, nicotine withdrawal tremors in the first days after birth, delays in learning to use language sounds lead-
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ing to delayed speech development, impulsiveness and hyperactivity, and a slightly lower
IQ (Fried, James, & Watkinson, 2001; Fried & Watkinson, 2001). These effects were lessened if mothers reduced or stopped smoking during pregnancy. A more recent concern involves maternal and infant exposure to environmental tobacco smoke (ETS), or
second-hand smoke. About 13 per cent of pregnant non-smokers in Canada report living
with a partner who smokes (Health Canada, 1999). ETS exposure appears to have the same
effects on prenatal and postnatal development as does smoking by pregnant women (Cornelius & Day, 2000), and in addition increases the risk of sudden infant death syndrome
(SIDS) and inner ear infection in infancy (Helgason & Lund, 2001).
Caffeine Can the caffeine a pregnant woman swallows in coffee, tea, cola, or chocolate
cause trouble for her fetus? For the most part, the answer is uncertain. It does seem clear
that caffeine is not a teratogen for human babies (Hinds, West, Knight, & Harland, 1996).
A controlled study of 1,205 new mothers and their babies showed no effect of reported
caffeine use on low birth weight, premature birth, or retarded fetal growth (Santos, Victora,
Huttly, & Carvalhal, 1998). On the other hand, four or more cups of coffee a day may
dramatically increase the risk of sudden death in infancy (Ford et al., 1998; see chapter 6).
In some research, caffeine consumption has been associated with spontaneous abortion
(Dlugosz et al., 1996; Infante-Rivard, Fernández, Gauthier, David, & Rivard, 1993), with
risk of first-trimester spontaneous abortion increasing with amount of caffeine consumed
(Cnattingius, Signorello et al., 2000). Other studies suggest that moderate caffeine use—
five cups a day or less—does not increase the risk of miscarriage (Klebanov, Levine, DerSimonian, Clemens, & Wilkins, 1999; Mills et al., 1993).
A woman who drinks and smokes
while pregnant is taking grave risks
with her future child’s health.
Marijuana, Opiates, and Cocaine Although findings about marijuana use by pregnant
women are mixed (Dreher, Nugent, & Hudgins, 1994; Lester & Dreher, 1989), some
evidence suggests that heavy use can lead to birth defects. A Canadian study found temporary neurological disturbances, such as tremors and startles, as well as higher rates of low
birth weight in the infants of marijuana smokers (Fried, Watkinson, & Willan, 1984).
An analysis of blood samples from the umbilical cords of 34 newborns found a
greater prevalence of cancer-causing mutations in the infants of mothers who smoked
marijuana. These women did not use tobacco, cocaine, or opiates, suggesting that
marijuana use alone can increase cancer risk (Ammenheuser, Berenson, Babiak, Singleton,
& Whorton, 1998).
Women addicted to morphine, heroin, and codeine are likely to bear premature, addicted
babies who will be addicted to the same drugs and will suffer the effects until at least age 6
(Hulse, O’Neill, Pereira, & Brewer, 2001). Prenatally exposed newborns are restless and irritable and often have tremors, convulsions, fever, vomiting, and breathing difficulties (Henly
& Fitch, 1966; Ostrea & Chavez, 1979). Those who survive cry often, are less alert and less
responsive than other babies (Strauss, Lessen-Firestone, Starr, & Ostrea, 1975) and tend to
show acute withdrawal symptoms during the neonatal period, requiring prompt treatment
(Wagner, Katikaneni, Cox, & Ryan, 1998). Although methadone is the standard medical treatment for heroin addiction in pregnancy, because it can reduce some harmful effects of heroin,
like low birth weight (Kandall, Doberczak, Jantunen, & Stein, 1999), there are concerns about
its safety in cases of women who continue using heroin while taking methadone. This combination results in greater risk of neonatal mortality than if no methadone were taken (Hulse
& O’Neill, 2001) and lower birth weight than would be expected if only methadone were
used (Hulse, Milne, English, & Holman, 1997). Moreover, methodone use in pregnancy results in abnormal non-stress tests of neonatal heart rate, indicating changes in neural responsiveness in the fetus (Anyaegbunam, Tran, Jadali, Randolph, & Mikhail, 1997). Alternatives
to methadone are being investigated, but with uncertain efficacy compared to methadone (Annitto, 2000; Marquet, Chevrel, Lavignasse, Merle, & Lachatre, 1997).
At 1 year, these infants are likely to show somewhat slowed psychomotor development
(Bunikowski et al., 1998). In early childhood they weigh less, are shorter, are less well adjusted, and score lower on tests of perceptual and learning abilities (Wilson, McCreary,
Kean, & Baxter, 1979). These children tend not to do well in school, to be unusually anxious in social situations, and to have trouble making friends (Householder, Hatcher, Burns,
& Chasnoff, 1982).
Chapter 4
Pregnancy and Prenatal Development
85
A pregnant woman’s use of cocaine is associated with a higher risk of spontaneous
abortion, prematurity, low birth weight, and small head size. “Cocaine babies” are generally not as alert as other babies and not as responsive, either emotionally or cognitively; or
they may be more excitable, more irritable, and less able to regulate their sleep–wake patterns (Alessandri, Sullivan, Imaizumi, & Lewis, 1993; Kliegman, Madura, Kiwi, Eisenberg, & Yamashita, 1994; Napiorkowski et al., 1996; Ness et al., 1999; Phillips, Sharma,
Premachandra, Vaughn, & Reyes-Lee, 1996; Singer et al., 1994; Tronick, Frank, Cabral,
Mirochnick, & Zuckerman, 1996).
These infants may show impaired motor activity (Fetters & Tronick, 1996) or excessive activity, as well as extreme muscular tension, jerky movements, startles, tremors, and
other signs of neurological stress (Napiorkowski et al., 1996). They tend to have trouble
regulating attention (Mayes, Granger, Frank, Schottenfeld, & Bornstein, 1993) and emotional arousal. When interrupted, frustrated, or upset, it is hard for them to “regroup,” recover, and move on (Bendersky, Alessandri, & Lewis, 1996; Bendersky & Lewis, 1998).
Electroencephalographic (EEG) measurements of sleep patterns indicate subtle impairments in neurological development at birth and at 1 year (Scher, Richardson, & Day, 2000).
The more cocaine a woman takes while pregnant, the greater the odds of impaired fetal
growth and neurological functioning (Chiriboga, Brust, Bateman, & Hauser, 1999).
A cocaine baby’s inactivity, lethargy, irritability, or unresponsiveness may frustrate the
mother and prevent her from forming a close, caring relationship with her infant. On the
other hand, it may be that cocaine-exposed infants do not learn to regulate and express their
emotions because their cocaine-using mothers are less sensitive and responsive than other
mothers (Alessandri, Sullivan, Bendersky, & Lewis, 1995; Bendersky et al., 1996;
Bendersky & Lewis, 1998; Phillips et al., 1996).
Physically, some cocaine-exposed infants do recover. Especially if they had good prenatal care, they often catch up in weight, length, and head circumference by 1 year of age
(Racine, Joyce, & Anderson, 1993; Weathers, Crane, Sauvain, & Blackhurst, 1993). However, deficiencies in motor control, especially hand use and eye–hand coordination, have
been found at age 2 (Arendt, Angelopoulos, Salvator, & Singer, 1999). Psychosocial effects
tend to last longer; cocaine-exposed children show a tendency toward such behavioural
problems as aggressiveness and anxiety, especially when under stress (Azar, 1997). Exposure to low levels of cocaine seems to have little long-term effect on cognition, but exposure to high levels may lead to difficulties, especially in learning complex skills
(Alessandri, Bendersky, & Lewis, 1998).
acquired immune deficiency
syndrome (AIDS) Viral disease
that undermines effective
functioning of the immune system
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Part 2
Beginnings
Sexually Transmitted Diseases and Other Maternal Illnesses
Acquired immune deficiency syndrome (AIDS) is a disease caused by the human immunodeficiency virus (HIV), which undermines functioning of the immune system. If an
expectant mother has the virus in her blood, it may cross over to the fetus’s bloodstream
through the placenta. After birth, the virus can be transmitted through breast milk.
Important advances have been made in the prevention, detection, and treatment of HIV
infection in infants. These include the successful use of the drug zidovudine (formerly
azidothymidine), commonly called AZT, to curtail transmission; the recommendation that
women with HIV should not breast-feed; and the availability of new drugs to treat AIDSrelated pneumonia. Between 1992 and 1997, when zidovudine therapy became widespread,
the number of babies who got AIDS from their mothers dropped by about two-thirds,
raising the hope that mother-to-child transmission of the virus can be virtually eliminated
(Lindegren et al., 1999). The risk of transmission also can be reduced by choosing Caesarean delivery (International Perinatal HIV Group, 1999).
Prospects for children born with HIV infection have improved. The progress of the disease, at least in some children, seems slower than was previously thought. While some develop full-blown AIDS by their first or second birthday, others live for years with little
apparent effect if any at all (European Collaborative Study, 1994; Grubman et al., 1995;
Nielsen et al., 1997; Nozyce et al., 1994).
Syphilis can cause problems in fetal development, and gonorrhea and genital herpes
can have harmful effects on the baby at the time of delivery. The incidence of genital herpes simplex virus (HSV) has increased among newborns, who may acquire the disease
from the mother or father either at or soon after birth (Sullivan-Bolyai, Hull, Wilson, &
Corey, 1983), causing blindness, other abnormalities, or death. Again, Caesarean delivery
may help avoid infection.
Other maternal illnesses can lead to health problems in the child. A diabetic mother’s
metabolic regulation, especially during the second and third trimesters of pregnancy, unless
carefully managed, may affect her child’s long-range neurobehavioural development and
cognitive performance (Rizzo, Metzger, Dooley, & Cho, 1997). Risks of diabetic pregnancies can be greatly reduced by screening pregnant women for diabetes, followed by careful
monitoring and a controlled diet (Kjos & Buchanan, 1999).
Both prospective parents should try to prevent all infections—common colds, flu, urinary tract and vaginal infections, as well as sexually transmitted diseases. If the mother
does contract an infection, she should have it treated promptly. Pregnant women also
should be screened for thyroid deficiency, which can affect their children’s future cognitive
performance (Haddow et al., 1999).
Rubella (German measles), if contracted by a woman before her 11th week of pregnancy, is almost certain to cause deafness and heart defects in her baby. Chances of catching rubella during pregnancy have been greatly reduced in Canada since the late 1960s,
when a vaccine was developed that is now routinely administered to infants and children
(CICH, 2000). However, rubella is still a serious problem in non-industialized countries
where inoculations are not routine (Plotkin, Katz, & Cordero, 1999).
Maternal Age
Women today typically start having children later in life than was true 15 or 20 years ago,
often because they spend their early adult years getting advanced education and establishing careers (Canadian Institute of Child Health [CICH], 2000; Mathews & Ventura, 1997;
Ventura et al., 1999). About a third of all Canadian babies are born to women over the age
of 30 (Canadian Institute of Child Health, 2000).
How does delayed childbearing affect the risks to mother and baby? Pregnant women
who are older are more likely to suffer complications due to diabetes, high blood pressure,
or severe bleeding. Most risks to the infant’s health are not much greater than for babies
born to younger mothers. Still, after age 35 there is more chance of miscarriage or stillbirth,
and more likelihood of premature delivery, retarded fetal growth, other birth-related complications, or birth defects, such as Down syndrome (refer back to chapter 3). However, due
to widespread screening for fetal defects among older expectant mothers, fewer babies with
prenatally identified defects are born nowadays (Berkowitz, Skovron, Lapinski, &
Berkowitz, 1990; P. Brown, 1993; Cunningham & Leveno, 1995).
Women age 40 and over are at increased risk of needing operative deliveries (Caesarean or by forceps or vacuum extraction—see chapter 5). Risks of all birth complications
are increased, and the infants are more likely to be born prematurely and underweight
(Gilbert, Nesbitt, & Danielsen, 1999).
Adolescents also tend to have premature or underweight babies—perhaps because a
young girl’s still-growing body consumes vital nutrients the fetus needs (Fraser, Brockert,
& Ward, 1995). These newborns are at heightened risk of death in the first month, disabilities, or health problems. If teenage mothers are unwed, they are likely to suffer great financial hardship and may drop out of school, narrowing their future vocational choices.
And, try as they may to do their best at mothering, their lack of parenting skills may put
their babies at a disadvantage (AAP Committee on Adolescence, 1999; Alan Guttmacher
Institute, 1999a; Children’s Defense Fund, 1998). Risks of teenage pregnancy are discussed
further in chapter 17.
Outside Environmental Hazards
Chemicals, radiation, extremes of heat and humidity, and other hazards of modern life can
affect prenatal development. Women who work with chemicals used in manufacturing semiconductor chips have about twice the rate of miscarriage as other female workers (Markoff,
1992). Infants exposed prenatally to high levels of lead score lower on tests of cognitive
abilities than those exposed to low or moderate levels (Bellinger, Leviton, Watermaux,
Chapter 4
Can you . . .
✔ Describe the short-term and
long-term effects on the
developing fetus of a mother’s
use of medical drugs, alcohol,
tobacco, caffeine, marijuana,
opiates, and cocaine during
pregnancy?
✔ Summarize the risks of
maternal illnesses, delayed
childbearing, and exposure to
chemicals and radiation?
Pregnancy and Prenatal Development
87
Needleman, & Rabinowitz, 1987; Needleman & Gatsonis, 1990). Children exposed prenatally
to heavy metals have higher rates of childhood illness and lower measured intelligence than
children not exposed to these metals (Lewis, Worobey, Ramsay, & McCormack, 1992).
Radiation can cause genetic mutations. Nuclear radiation affected Japanese infants after the atomic bomb explosions in Hiroshima and Nagasaki (Yamazaki & Schull, 1990) and
infants as far away as Germany after the spill-out at the nuclear power plant at Chernobyl in
the Soviet Union (West Berlin Human Genetics Institute, 1987). In utero exposure to radiation has been linked to greater risk of mental retardation, small head size, chromosomal malformations, Down syndrome, seizures, and poor performance on IQ tests and in school. The
critical period seems to be 8 through 15 weeks after fertilization (Yamazaki & Schull, 1990).
Paternal Factors
• Since cocaine, marijuana,
tobacco, and other
substances can produce
genetic abnormalities in a
man’s sperm, should fertile
men be forced to abstain from
them? How could such a
prohibition be enforced?
Can you . . .
✔ Identify at least three ways in
which environmentally caused
defects can be influenced by
the father?
The father, too, can transmit environmentally caused defects. A man’s exposure to lead,
marijuana or tobacco smoke, large amounts of alcohol or radiation, DES, or certain pesticides may result in abnormal sperm. Offspring of male workers at a British nuclear processing plant were found to have an elevated risk of being born dead (Parker, Pearce,
Dickinson, Aitkin, & Craft, 1999). Also, babies whose fathers had diagnostic X-rays within
the year prior to conception tend to have low birth weight and slowed fetal growth (Shea,
Little, & the ALSPAC Study Team, 1997). And fathers whose diet is low in vitamin C are
more likely to have children with birth defects and certain types of cancer (Fraga et al.,
1991). A study of 2000 farm couples showed that preconception exposure to herbicides by
fathers resulted in an increased risk of early miscarriage (Arbuckle, Savitz, Mery, & Curtis, 1999). Pesticide residues have been found in samples of semen of farmers, which could
account for the increased risk of early miscarriage (Arbuckle, Schrader, Cole, Hall, Bancej,
Turner, & Claman, 1999).
A man’s use of cocaine can cause birth defects in his children. The cocaine seems to
attach itself to his sperm, and this cocaine-bearing sperm then enters the ovum at conception. Other toxins, such as lead and mercury, may “hitchhike” onto sperm in the same way
(Yazigi, Odem, & Polakoski, 1991).
Older fathers may be a significant source of birth defects (Crow, 1993, 1995). A later
paternal age (averaging in the late thirties) is associated with increases in the risk of several
rare conditions, including Marfan’s syndrome (deformities of the head and limbs) and
dwarfism (G. Evans, 1976). Advanced age of the father may also be a factor in about 5 per
cent of cases of Down syndrome (Antonarakis & Down Syndrome Collaborative Group,
1991). More male cells than female ones undergo mutations, and mutations may increase
with paternal age.
A father’s smoking is a harmful environmental influence, which has been linked with
low birth weight and cancer in childhood and adulthood ((Ji et al., 1997; D. H. Rubin,
Krasilnikoff, Leventhal, Weile, & Berget, 1986; Sandler, Everson, Wilcox, & Browder,
1985). Paternal smoking brings increased risk of infant respiratory infections and sudden
infant death, whether or not the mother also smokes (Wakefield, Reid, Roberts, Mullins, &
Gillies, 1998).
Guidepost 4
What techniques can assess a
fetus’s health and well-being,
and what is the importance of
prenatal care?
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Part 2
Beginnings
Monitoring Prenatal Development
Not long ago, almost the only decision parents had to make about their babies before birth
was the decision to conceive; most of what happened in the intervening months was beyond
their control. Now we have an array of tools to assess an unborn baby’s progress and wellbeing (see Box 4-2), and even to intervene to correct some abnormal conditions. In line
with these developments is a growing emphasis on the importance of early prenatal care.
Conditions detected by prenatal assessment can be corrected before birth in three
ways: administration of medicine, blood transfusion, and surgery. Fetuses can swallow and
absorb medicines, nutrients, vitamins, and hormones that are injected into the amniotic
fluid, and drugs that might not pass through the placenta can be injected through the umbilical cord. Blood can be transfused through the cord as early as the 18th week of gesta-
The Everyday World
Box 4-2
Prenatal Assessment Techniques
Normal prenatal development is overwhelmingly the rule. Still,
we need to be aware of the many ways development can go awry
and how best to avoid problems. Techniques for monitoring fetal
development, coupled with increased knowledge of ways to improve the child’s prenatal world, make pregnancy much less a
cause for concern than in earlier times. Access to prenatal diagnosis of birth defects, coupled with the legal availability of abortion
and the possibility of fetal therapy, have encouraged many couples
with troubling medical histories to take a chance on conception.
Ultrasound and Amniocentesis
Some parents see their baby for the first time in a sonogram, a
picture of the uterus, fetus, and placenta created by ultrasound directed into the mother’s abdomen. Ultrasound is used to measure
fetal growth, to judge gestational age, to detect multiple pregnancies, to evaluate uterine abnormalities, to detect major structural
abnormalities in the fetus, and to determine whether a fetus has
died, as well as to guide other procedures, such as amniocentesis.
A newer technique called sonoembryology, which involves
high-frequency transvaginal probes and digital image processing, has made possible earlier detection of unusual defects during the embryonic stage. Sonoembryology reportedly can detect
60 per cent of all malformations during the first trimester of
pregnancy and, in combination with ultrasound, more than 80
per cent during the second trimester (Kurjak, Kupesic, Matijevic,
Kos, & Marton, 1999).
In amniocentesis, a sample of the amniotic fluid, which contains
fetal cells, is withdrawn and analyzed to detect the presence of certain genetic or multifactorial defects and all recognizable chromosomal disorders. Only 3.2 per cent of mothers who had live births
used amniocentesis in 1996, as compared with 64 per cent who had
ultrasound (Ventura, Martin, Curtin, & Mathews, 1998). Amniocentesis is recommended for pregnant women aged 35 and over. It
is also recommended if the woman and her partner are both known
carriers of such diseases as Tay-Sachs and sickle-cell anemia, or if
they have a family history of such conditions as Down syndrome,
spina bifida, Rh disease, and muscular dystrophy.
Amniocentesis is usually done between the 15th and 18th
weeks of pregnancy. Women who have the test earlier may
greatly increase their risk of miscarriage, which is more common
during the first trimester. A randomized Canadian study found a
7.6 per cent rate of fetal loss when amniocentesis was done between the 11th and 12th weeks of gestation, as compared with
5.9 per cent between the 15th and 16th weeks (Canadian Early
and Mid-Trimester Amniocentesis Trial [CEMAT] Group, 1998).
Both amniocentesis and ultrasound can reveal the sex of the fetus, which may help in diagnosing sex-linked disorders. In some
Asian countries in which sons are preferred, both procedures have
been used (in some places, illegally) for “sex-screening” of unborn
babies, with the result that in these populations males now predominate (Burns, 1994; Kristof, 1993; WuDunn, 1997). Such
early sex-screening is not supported in Canada except in the case
of possible sex-linked disorders. In the recently introduced Act
Respecting Assisted Human Reproduction, identifying the sex of
an embryo that was created using assisted reproductive technology is prohibited except for medical reasons.
Other Assessment Methods
In chorionic villus sampling (CVS), tissue from the ends of
villi—hairlike projections of the chorion, the membrane sur-
rounding the fetus, which are made up of fetal cells—are tested
for the presence of birth defects and disorders. This procedure
can be performed between 8 and 13 weeks of pregnancy (earlier
than amniocentesis), and it yields results within about a week.
However, there is almost a 5 per cent greater chance of miscarriage or neonatal death after CVS than after amniocentesis
(D’Alton & DeCherney, 1993).
Embryoscopy, insertion of a tiny viewing scope into a pregnant woman’s abdomen, can provide a clear look at embryos as
young as 6 weeks. The procedure is promising for early diagnosis and treatment of embryonic and fetal abnormalities
(Quintero, Abuhamad, Hobbins, & Mahoney, 1993).
Preimplantation genetic diagnosis can identify some genetic
defects in embryos of four to eight cells, which were conceived
by in vitro fertilization and have not yet been implanted in the
mother’s uterus. Defective embryos are not implanted.
By inserting a needle into tiny blood vessels of the umbilical
cord under the guidance of ultrasound, doctors can take samples
of a fetus’s blood. This procedure, called umbilical cord sampling
or fetal blood sampling, can test for infection, anemia, heart failure, and certain metabolic disorders and immunodeficiencies and
seems to offer promise for identifying other conditions. However,
the technique is associated with miscarriage, bleeding from the
umbilical cord, early labour, and infection (Chervenak, Isaacson,
& Mahoney, 1986; D’Alton & DeCherney, 1993; Kolata, 1988).
A blood sample taken from the mother between the 16th and
18th weeks of pregnancy can be tested for the amount of alpha fetoprotein (AFP) it contains. This maternal blood test is appropriate for women at risk of bearing children with defects in the
formation of the brain or spinal cord, such as anencephaly or spina
bifida, which may be detected by high AFP levels. To confirm or
refute the presence of suspected conditions, ultrasound or amniocentesis, or both, may be performed. Blood tests of samples taken
between the 15th and 20th weeks of gestation can predict about 60
per cent of cases of Down syndrome. This blood test is particularly
important for women under 35, who bear 80 per cent of all Down
syndrome babies but usually are not targeted to receive amniocentesis because their personal risk is lower (Haddow et al., 1992).
The discovery that fetal cells that “leak” into the mother’s blood
early in pregnancy can be isolated and analyzed (Simpson & Elias,
1993) will make it possible to detect genetic as well as chromosomal disorders from a maternal blood test without using riskier procedures, such as amniocentesis, chorionic villus sampling, and fetal
blood sampling. Already researchers have succeeded in screening
fetal blood cells for single genes for sickle-cell anemia and thalassemia (Cheung, Goldberg, & Kan, 1996).
?
What’s your view
In Canada, women who undergo ultrasound or amniocentesis often are given the choice of whether or not they will be told their
unborn babies’ sex. Suppose it became known that substantial
numbers of Canadian women were aborting their fetuses for reasons of sex preference, as has happened in some East Asian
countries. In that case, would you favour a law forbidding use of
a prenatal diagnostic procedure to reveal the sex of a fetus?
!
Check it out
For more information on this topic, go to www.mcgrawhill.ca/
college/papalia.
Chapter 4
Pregnancy and Prenatal Development
89
100
Newfoundland
90
British Columbia
Saskatchewan
Infant Deaths per 1,000 Live Births
80
Alberta
New Brunswick
Manitoba
Prince Edward Island
Yukon
Nova Scotia
Quebec
Ontario
Northwest Territories
70
60
50
40
30
20
10
1961–65
1971–75
1981–85
1991–95
Figure 4-3
Infant mortality rates in Canadian provinces and territories 1961–65 to 1991–95.
Source: Dzakpasu, S. et al. The Matthew Effect: Infant Mortality in Canada and Internationally, Pediatrics 106 p. 2
• Can you suggest ways to
induce more pregnant women
to seek early prenatal care?
90
Part 2
Beginnings
tion. In 1996, surgeons successfully performed a bone marrow transplant in the womb to
prevent the development of a rare sex-linked genetic disorder, severe combined immunodeficiency, in a fetus identified by chorionic villus sampling as having the mutant gene for
it. The baby was born healthy by Caesarean delivery and showed no sign of the disorder
throughout infancy (Flake et al., 1996). Eventually transplantation procedures, in the form
of gene therapy, may be used to treat other congenital diseases in utero.
Screening for treatable defects and diseases is only one reason for the importance of
prenatal care. Early, high-quality prenatal care, which includes educational, social, and nutritional services, can help prevent maternal and infant death and other complications of
birth. It can provide first-time mothers with information about pregnancy, childbirth, and
infant care. Poor women who get prenatal care benefit by being put in touch with other
needed services, and they are more likely to get medical care for their infants after birth
(Shiono & Behrman, 1995).
In Canada prenatal care is widespread, but despite universal health insurance, socioeconomic status affects the quality of prenatal care provided to pregnant women (Canadian
Perinatal Surveillance System, 2000). As an indicator of different effectiveness of prenatal
care, low-income groups experience over 150 per cent the infant mortality rate of higherincome groups. However, the disparity in infant mortality rates between income groups and
between regions in Canada is decreasing (Dzakpasu, Joseph, Kramer, & Allen, 2000; see
Figure 4-3).
Even as usage of prenatal care has increased, rates of low birthweight and premature
birth have worsened (Kogan et al., 1998; Ventura et al., 1999). Why?
One answer is the increasing number of multiple births, which require especially close
prenatal attention. Twin pregnancies often end, for precautionary reasons, in early births,
either induced or by Caesarean delivery. Intensive prenatal care may allow early detection
of problems requiring immediate delivery, as, for example, when one or both fetuses are not
thriving. This may explain why a Canadian study of twin births between 1986 and 1997
found parallel upward trends in use of prenatal care and rates of preterm birth—along with
a decline in mortality of twin infants (Joseph, Marcoux, Ohlsson, Liu, Allen, Kramer, &
Wen, 2001).
Another possible explanation for these parallel trends is that the benefits of prenatal
care are not evenly distributed, particularly in Northern and remote communities. Merely
increasing the quantity of prenatal care does not address the content of care (Misra &
Guyer, 1998). Most prenatal care programs in Canada focus on screening for major complications and are not designed to attack the causes of low birth weight. A U.S. national
panel has recommended that prenatal care be restructured to provide more visits early in
the pregnancy and fewer in the last trimester. In fact, care should begin before pregnancy.
Prepregnancy counselling could make more women aware, for example, of the importance
of getting enough folic acid in their diet and making sure that they are immune to rubella.
In addition, care needs to be made more accessible to poor and minority women (Shiono &
Behrman, 1995).
Good prenatal care can give every child the best possible chance for entering the world
in good condition to meet the challenges of life outside the uterus—challenges we discuss
in the next three chapters.
Can you . . .
✔ Describe seven techniques for
identifying defects or disorders
prenatally?
✔ Tell why early, high-quality
prenatal care is important, and
how it could be improved?
Summary and Key Terms
Prenatal Development: Three Stages
Guidepost 1 What are the three stages of prenatal development,
and what happens during each stage?
• Prenatal development occurs in three stages of gestation: the
germinal, embryonic, and fetal stages.
• Growth and development both before and after birth follow
the cephalocaudal principle (head to tail) and the
proximodistal principle (centre outward).
• About one-third of all conceptions end in spontaneous
abortion, usually in the first trimester of pregnancy.
cephalocaudal principle (75) proximodistal principle (75)
germinal stage (75) embryonic stage (78)
spontaneous abortion (78) fetal stage (79)
Guidepost 2 What can fetuses do?
• As fetuses grow, they move less, but more vigorously.
Swallowing amniotic fluid, which contains substances from
the mother’s body, stimulates taste and smell. Fetuses seem
able to hear, exercise sensory discrimination, learn, and
remember.
ultrasound (79)
Prenatal Development: Environmental
Influences
Guidepost 3 What environmental influences can affect prenatal
development?
• The developing organism can be greatly affected by its
prenatal environment. The likelihood of a birth defect may
depend on the timing and intensity of an environmental event
and its interaction with genetic factors.
• Important environmental influences involving the mother
include nutrition, physical activity, smoking, intake of alcohol
or other drugs, transmission of maternal illnesses or infections,
maternal age, incompatibility of blood type, and external
environmental hazards, such as chemicals and radiation.
External influences may also affect the father’s sperm.
teratogenic (80) fetal alcohol syndrome (FAS) (83)
acquired immune deficiency syndrome (AIDS) (86)
Monitoring Prenatal Development
Guidepost 4 What techniques can assess a fetus’s health and
well-being, and what is the importance of prenatal care?
• Ultrasound, amniocentesis, chorionic villus sampling,
embryoscopy, preimplantation genetic diagnosis, umbilical
cord sampling, and maternal blood tests can be used to
determine whether an unborn baby is developing normally.
Some abnormal conditions can be corrected through fetal
therapy.
• Early, high-quality prenatal care is essential for healthy
development. It can lead to detection of defects and disorders
and, especially if begun early and targeted to the needs of atrisk women, may help reduce maternal and infant death, low
birth weight, and other birth complications.
OLC Preview
The Online Learning Centre for A Child’s World, First Canadian
Edition, offers information on traditional cultures and new technology and on pregnancy in the 21st century, as well as links to recom-
mended websites on fetal welfare versus mothers’ rights and
prenatal assessment techniques. Check out www.mcgrawhill.ca/
college/papalia.
Chapter 4
Pregnancy and Prenatal Development
91